Adverse Events After Surgical Treatment of Adult Diaphyseal Forearm Fractures

Background: The incidence of and risk factors for adverse events after internal fixation of diaphyseal forearm fractures have not been well defined in the current literature. The objective of this study was to estimate the incidence of adverse events after diaphyseal forearm fracture surgery in adults and explore potential risk factors for adverse events. Methods: We conducted a retrospective, multicenter, cohort study in which we evaluated all diaphyseal forearm fractures between 2009 and 2019 in patients presenting to 4 trauma hospitals in southern Finland. Patients <16 years of age and fracture-dislocations were excluded. There were 470 patients included in this study. Patient records were evaluated to identify and analyze adverse events. Results: There were 202 patients with both-bone fractures, 164 patients with isolated ulnar fractures, and 104 patients with isolated radial fractures. In total, 146 patients (31%) experienced an adverse event; 83 (18%) had major adverse events (persistent or requiring surgical intervention). The patients underwent procedures performed by 185 different surgeons. The median number of operations for a single surgeon was 2 (range, 1 to 12). The most common major adverse events were plate and screw-related issues (6%), nonunion (5%), persistent nerve injuries (4%), and refractures (4%). Higher body mass index, Gustilo-Anderson type-II open fractures, both-bone fractures, isolated radial fractures, and operations performed by junior residents were found to be risk factors for adverse events in the multivariable analysis. Conclusions: Adverse events after diaphyseal forearm fracture surgery are common. We recommend concentrating these operations in a limited team of surgeons and restricting inexperienced surgeons from operating on these fractures without supervision. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

L oss of forearm function substantially affects the quality of life 1 . Therefore, a diaphyseal forearm fracture endangers the function of the affected extremity. Compared with distal forearm fractures, the injury mechanism in diaphyseal fractures is more often high-energy trauma, and diaphyseal fractures are more often seen in the working-age population 2,3 .
Consequently, adequate fracture reduction and fixation are crucial, and nonoperative treatment is rarely favored 4,5 . Indications for cast immobilization include isolated singlebone fractures with minimal displacement, angulation, and rotation and fractures that are considered inoperable because of considerable patient comorbidities 6 . Even minimally displaced both-bone forearm fractures are prone to more displacement, malunion, and nonunion 7 . Thus, open reduction and internal fixation with compression plating is used to manage most forearm fractures to enable rapid union and restoration of forearm anatomy 6 .
To our knowledge, no risk factors for adverse events have been identified, as all publications have had insufficient patient numbers for risk factor analysis. Despite the importance of forearm function in daily activities 15 , current knowledge regarding complications in these fractures is mainly premised on older publications [9][10][11] . Only a few articles have been published in the last decade 13,14,16 .
The objective of this study was to estimate the incidence of adverse events in surgically treated diaphyseal forearm fractures (both-bone, isolated radial, and isolated ulnar fractures) in adults and identify possible risk factors for adverse events.

Materials and Methods
Setting and Inclusion Criteria W e performed a retrospective, multicenter, cohort study of patients from 4 hospitals in southern Finland (1 Level-I trauma center and 3 Level-II trauma centers). The chosen hospitals are the only public hospitals in their area with an oncall orthopaedic surgeon at all times, with a population base of 2.2 million residents 17 . Between January 2009 and December 2019, patients who were ‡16 years of age and had diaphyseal forearm fractures were identified (see Appendix Table 1). The diaphyseal region of the forearm was defined on the basis of OTA/AO guidelines 18 . Furthermore, we excluded Galeazzi and Monteggia fracture-dislocations from the study. Comprehensive inclusion and exclusion criteria are presented in Figure 1. A total of 470 patients were included in the analysis.
The participating hospitals' institutional boards approved this study. An ethical committee approval or informed patient consent was not required, as the study did not involve any patient interaction.

Follow-up
The patient records were evaluated for a minimum of 2 years postoperatively. By protocol, only a single follow-up visit was

Perioperative Information
We collected demographic data and comorbidities from the patient database (Table I). Standard anteroposterior and lateral forearm radiographs were available for all patients. In addition, computed tomography (CT) scans were examined if available. The authors classified all fractures according to the OTA/AO classification 18 . Open fractures were further classified on the basis of the Gustilo-Anderson classification system 19 (Fig. 1).

Fracture Treatment
The treatment followed the surgical guidelines proposed by the AO Foundation 6 . All fractures were definitively managed with open reduction and internal fixation with plates. Prophylactic antibiotics were administered to all patients during anesthesia induction. A cast was placed according to the operating surgeon's preference. Fracture reduction was considered adequate if angulation was <10°, rotation was <10°, and cortical displacement was <2 mm. We recorded the operating surgeons' status and divided them accordingly: junior resident, senior orthopaedic resident, senior hand surgery resident, orthopaedic consultant, and hand surgery consultant. Junior residents had <3 years of surgical experience, whereas senior residents had ‡3 years of experience, especially in the particular specialty. In addition, we recorded whether a consultant surgeon was supervising or ‡The values are given as the number of patients, with the percentage (with respect to the group in question) in parentheses. §200 patients had missing data: 75 in the ulnar fracture group, 51 in the radial fracture group, and 74 in the bothbone fracture group. #6 patients had missing data: 4 in the ulnar fracture group and 2 in the both-bone fracture group. Low-energy fracture indicates fracture energy equivalent to a fall from a standing height; moderate-energy fracture indicates a fall from 1 to 3 m, a motor vehicle injury with speed <30 km/hr, or the equivalent; and high-energy fracture indicates a fall from >3 m, a motor vehicle injury with speed >30 km/hr, or the equivalent. **69 patients had missing data: 23 in the ulnar fracture group, 7 in the radial fracture group, and 39 in the both-bone fracture group. Age and sex distribution of surgically treated diaphyseal forearm fractures. Each bar represents 2 years.

Adverse Events After Surgical Treatment of Adult Diaphyseal Forearm Fractures
JBJS Open Access d 2023:e22.00115. openaccess.jbjs.org assisting with the procedure and determined the overall number of diaphyseal forearm fracture procedures performed during the research period for each surgeon. The primary fixation methods used in the operations are presented in Table I. Dynamic compression, semitubular, onethird tubular, and reconstruction plates were classified as nonconventional plates. An external fixator device was used as a temporary fixation method in 5 patients.

Adverse Event Definitions
An adverse event was defined as any deviation from the normal postoperative course 20 . We recorded all postoperative adverse events and divided them into major and minor categories. Persistent adverse events that did not show apparent signs of resolution during the clinical follow-up and adverse events requiring secondary operations were considered major adverse events. We did not include preoperative adverse events as they depended largely on the injury. In cases with uncertainty regarding whether the adverse event was preoperative or postoperative, the adverse events were included in the analysis.
We assessed fracture union on the basis of follow-up radiographs. Radiographs for the patients included in the study were available until there were clear clinical and radiographic signs of fracture healing. A nonunion was diagnosed if fracture union required a secondary operation or took >6 months. The fracture union was considered delayed if it took 3 to 6 months. Surgical site infections were divided into deep and superficial infections according to the U.S. Centers for Disease Control and Prevention criteria 21 . A nerve injury was diagnosed in cases in which the nerve status had been intact preoperatively, but a physician observed paresthesia or paralysis postoperatively. The nerve damage was considered transient if it resolved during the first 4 months of follow-up. Other recorded adverse events included plate and screw-related issues and refractures  (refracture after plate removal or peri-implant fracture). All secondary operations were performed in the operating room.

Statistical Analysis
We reported descriptive statistics using cross-tabulations. Nominal variables are presented as counts and percentages. For variables with missing values, the percentages of the patients with values were compared. The skewness of the continuous variables was assessed with histograms and quantile-quantile (Q-Q) plots. As all continuous variables were skewed, we present them as medians and interquartile ranges (IQRs). We used the binominal proportional interval to calculate the 95% confidence intervals (CIs) for adverse event proportions. Risk factor analysis was performed using binary logistic regression. Odds ratios (ORs) were calculated for each potential risk factor. Pairwise deletion was conducted in the case of missing values. We performed univariable modeling and selected potential variables to undergo multivariable logistic regression. To reduce bias in the covariate selection, we constructed a directed acyclic graph (see Appendix Figure 1).  (Fig. 2).

Adverse Events
A total of 146 patients (31% [95% CI, 27% to 35%]) encountered adverse events (Table II). In 66 patients, all adverse events were considered minor and resolved during the follow-up without further interventions, whereas 83 †The reasons for plate removal were unsatisfactory placement (n = 3), unspecified pain (n = 2), and infection (n = 1). ‡Radioulnar synostosis excision. §Anterior interosseus nerve suturing. #A fibular graft to the radius after osteomyelitis and a fasciotomy.  (Table III). Nonunion was diagnosed in 23 patients (5% [95% CI, 3% to 7%]), and delayed union (3 to 6 months) was seen in 39 patients. In total, 18 patients with nonunion required at least 1 secondary operation (refixation with a bone graft) to achieve union, 2 of whom required multiple reoperations. The 5 patients with nonoperatively treated nonunion, all of whom had both-bone fractures, achieved satisfactory fracture union eventually (range, 45 to 81 weeks). With regard to possible risk factors for nonunion, all patients had sufficiently anatomical reduction, although 4 were managed with nonconventional plates. In addition, 8 had sustained an open fracture, 2 had had a deep infection, 4 smoked cigarettes, and 4 had a history of alcohol abuse.
Surgical site infection was diagnosed in 28 patients (6% [95% CI, 4% to 9%]), of whom 10 had deep surgical site infections and 18 had superficial surgical site infections; 12 of these patients had had an open fracture. Nine patients developed a deep infection following the primary operation, and 1 patient developed a deep infection following a secondary surgical procedure after nonunion. The patients with deep infections underwent a median of 1.5 revision surgical procedures (range, 1 to 2 procedures) to treat the infection. One patient with a grade-I, open, both-bone fracture developed osteomyelitis to the radius and required plate removal and external fixator application. Subsequently, a reconstruc-tion of the radius was performed with a fibular autograft. The other 9 patients were treated successfully without plate removal. Bacterial cultures were available in 6 deep infections; 2 of these were polymicrobial infections (see Appendix to 6%]), there were 5 affecting the median nerve, 5 affecting the radial nerve, 2 affecting the ulnar nerve, and 5 affecting multiple nerve branches (see Appendix Figure 2). Neurodiagnostic electroneuromyography was used to confirm the nerve damage in 15 cases. Of the persistent nerve injuries, 8 were considered sensory, 3 were considered motor, and 6 were considered combined. A nerve reconstruction surgeon was consulted in 10 cases, and end-to-end suturing was performed in 2 cases to treat iatrogenic nerve damage, 1 of which was performed during the initial operation. The other patients were managed nonoperatively.
There were 11 patients (2% [95% CI, 1% to 4%]) with fixation failure, of whom 8 were diagnosed as having a nonunion. All but 1 were managed with refixation (bone substitute was used with the 8 patients with nonunion). The remaining single fixation failure healed in a nonanatomical position with cast treatment. There were 15 patients whose main symptom was rotational deficiency. Seven of these patients had an unsatisfactory anatomical reduction and regained sufficient rotation after a secondary operation (5 early refixations and 2 corrective osteotomies), and 3 had unsatisfactory plate positioning and gained sufficient rotation after plate removal. Of the remaining patients with rotational deficiency, 2 had radioulnar synostosis, 2 were suspected of having soft-tissue scarring, and 1 had an unknown cause. During their follow-up period, 17 patients (4% [95% CI, 2% to 6%]) sustained a new fracture (13 peri-implant fractures and 4 refractures after plate removal). In total, the plate was removed from 21 patients, of whom 6 had an adverse event and 15 had removal at the patient's request with no compulsory clinical implications.

Risk Factor Analysis
The results of the univariable analysis are presented in Table IV. In the multivariable analysis, higher body mass index (BMI), both-bone and isolated radial fractures (compared with isolated ulnar fractures), type-II open fractures, and operations performed by junior residents were found to be risk factors for adverse events. When compared with a locking compression plate (LCP), nonconventional plates showed a nonsignificant trend toward more adverse events, whereas a limited contact dynamic compression plate (LC-DCP) showed a nonsignificant trend toward fewer adverse events (Table V).

Discussion
A dverse events after surgically treated diaphyseal forearm fractures are common. In the present study, 18% of the patients experienced major adverse events, and 31% had some sort of negative deviation in their postoperative course. Furthermore, 12% required at least 1 secondary operation due to adverse events. Adverse events were more common in bothbone and open fractures, with adverse event incidences as high as 40% for both-bone fractures and 43% for open fractures. The most frequent major adverse events were plate and screwrelated issues, nonunion, and nerve injuries.
In the limited number of publications since 2000, the combined adverse event incidence has been reported as 14% to 26% for diaphyseal forearm fractures using our criteria for adverse events 12,13,24,25 . However, the definitions of adverse events are often incomplete and vary between publications. Furthermore, those publications reported the incidence of adverse events separately, and minor adverse events and nerve injuries may have been underreported. Regardless, the adverse event incidence in the present study is high, even considering the factors affecting the comparison.
A concerning finding was that a single surgeon performed only a median of 2 operations during the study period. Even the surgeon with the most operations (12) would not qualify as a high-volume surgeon. A similar pattern was observed by Haas et al., as they had 108 different surgeons operating on 277 forearms 12 . It has been observed in several types of fractures that low-volume surgeons have a higher risk of adverse events, although evidence on forearm fractures has been lacking 26 . In our study, junior resident surgeons had significantly higher adverse event incidence than consultant surgeons (adjusted OR, 4.4 [95% CI, 1.9 to 10.3]), which indicates that patients who undergo procedures performed by inexperienced surgeons experience more adverse events. Based on our findings, we recommend concentrating these operations in a limited team of surgeons, restricting inexperienced surgeons from operating on these fractures without supervision, and performing complex cases with another surgeon. Nerve injuries have been discussed rarely in the publications that reported on diaphyseal forearm fracture adverse events. To our knowledge, reliable nerve damage incidence has only been reported by Iacobellis and Biz 13 and Marcheix et al. 14 .
In their studies, nerve damage was present in 8% to 9% of the cases. However, the criteria for the nerve injuries were unclear, and Marcheix et al. did not report whether the nerve injuries resolved during the follow-up. The incidence of nerve injuries was greater in our study (10%), although most of these resolved spontaneously during the follow-up. Overall, nerve injuries appear to play a more substantial role in the adverse event burden than previously thought.
Nonunion has been recognized as a major adverse event of forearm fracture surgery since the first considerable publications 5,9 . Nonunion incidence has been reported as 2% to 9% in recent decades. Furthermore, an additional 4% to 9% of patients have been reported to have a delayed union 13,14,24,27 . The nonunion incidence in our institution has been highly comparable with the literature. Accordingly, nonunion and delayed union remain a considerable issue that has yet to be solved.
In our study, the incidence of surgical site infections was 6%, with a deep infection incidence of 2%. The incidence was especially high in patients with open fractures. In the literature, the overall incidence of surgical site infections has been 1% to 2% 10,12,14 , with corresponding open fracture incidences of 21% to 32%. Whereas treating superficial infections is routine, little has been published on deep infections. Marcheix et al. reported a single deep infection treated successfully with a revision surgical procedure 14 , and Haas et al. reported 3 deep infections; 1 was treated with plate removal, 1 was treated with a revision surgical procedure, and 1 was treated with only antibiotics 12 . Because the knowledge on treating these infections has been limited, general methods for surgical site infections must be adapted.
There were several limitations to the study. First, we acquired the data retrospectively from hospital databases, and patient-reported outcomes were not available. Therefore, defining the impact of adverse events in practice is not well defined. However, the adverse events were described with precision, and the incidences are accurate. Second, the mean length of active follow-up was brief, and the patients were not contacted afterward. Although some adverse events might have been treated in other hospitals or private clinics, the hospitals in the study are the primary trauma hospitals in their area and have a high re-referral percentage if an adverse event arises. Finally, as we conducted an exploratory study testing different risk factors, we had to perform multiple statistical tests. However, we took considerable measures to avoid bias in the statistical analysis.
In conclusion, adverse events after diaphyseal forearm fracture surgery, including major adverse events, are common (31% and 18%, respectively). We recommend concentrating these operations in a limited team of surgeons, restricting inexperienced surgeons from operating on these fractures without supervision, and performing the complex cases with another surgeon, especially in both-bone and open fractures.